Mechanical fuze of the stator-rotor type with pivoted safety weights and detonator carrier



March 1967 G.T. KELLER ETAL 3,31

MECHANICAL FUZE OF THE STATOR-RQTOR TYPE WITH PIVOTED SAFETY WEIGHTS ANDDETONATOR CARRIER Filed June 9, 1965 INVENTORS.

GEORGE T. KELLER BY RONALD E BARKER ATTORNEYS.

United States Patent 3,311,060 MECHANICAL FUZE OF THE STATOR-ROTOR TYPEWITH PIVUTED SAFETY WEIGHTS AND DETONATOR CARRIER George T. 'Keller,Richmond, and Ronald F. Barker,

Centerville, Ind., assignors to Avco Corporation, Richmond, Ind.,acorporation of Delaware Filed June 9, 1965, Ser. No. 462,607 3 Claims.(Cl. 10279) ABSTRACT OF THE DISCLOSURE This mechanical fuze has anannular stator carrying a spring biased circular rotor. The statorcarries. two pivotally mounted safety weights and a pivotally mounteddetonator carrier, the pivot points being spaced by 120. Underspin-generated forces the weights swing outwardly and are unlocked fromthe rotor but the carriage holds the rotor until diminution ofcentrifugal forces permits the spring to turn the rotor, which rotor isformed to cause the safety weights and carriage element to be swunginwardly to arm the detonator.

The present invention relates to mechanical fuzes for utility in shells,grenades, rockets and similar devices which spin in flight. Thesedevices are hereinafter collectively referred to, for purposes ofbrevity, as missiles. It will be understood that conventionally the spinis clockwise looking into the base of the missile.

The principal object of the invention is to provide a relatively simplefuze mechanism consisting of a relatively small number of parts. Whileconventional mechanical fuze devices generally utilize severalcombinations of weights and springs in order to insure safety in thepresence of shock and vibration, together with additional devicesrequired to move a detonator from an out-of-line position to alignmentwith a firing train, the fuze in accordance with the invention utilizesonly a single spring and a relatively small number of moving parts.

In accordance with the invention there is provided:

In a mechanical fuze the combination of a rotor 11 having a plurality oflocking and positioning formations 25, 32 and 26, 33 and a holding andpositioning formation 30, energy storage means 12 urging the rotor inone angular direction (counterclockwise);

A stator A plurality of swingable centrifugal-force responsive safetyelements 13, 14 mounted on the stator and formed to engage the lockingportions 25, 26 of the locking and positioning formations on the rotorand to restrain the rotor against angular motion in said direction untila threshold of centrifugal force is attained, a detonator 19, aswingable centrifugal-f0roe-responsive detonator-carriage elementmounted on the stator and formed to engage the holding portion of theholding and positioning formation to cooperate in holding the rotoragainst movement in that direction until said threshold is attained, theattainment of such threshold swinging the safety elements sufficientlyoutward to disengage them from the locking portions and to engage themwith the positioning portions 32, 33 of the locking and positioningformations, whereupon the carriage element continues to engage theholding portion of the holding and positioning formation to hold therotor until the centrifugal force diminishes to such an extent as topermit the rotor to begin to turn in said direction whereupon the safetyelements and carriage element are positioned inwardly by theirrespective formations to place the detonator in armed position (inalignment with 21).

For a better understanding of the invention together with other andfurther objects, advantages and capabilities thereof, reference is madeto the following description of the accompanying drawings in which:

FIG. 1 is a front view of a fuze in accordance with the invention, withthe face plate removed;

FIG. 2 is an elevational sectional view as taken along section line 22of FIG. 1, looking in the direction of the arrows;

FIGS. 3, 4 and 5 are simplified front views provided to illustrate theconfigurations of the parts during the following phases of operation:safe, pre-arrned, and fully armed, respectively.

Making reference now particularly to FIGS. 1 and 2, the mechanical fuzethere shown is adapted to be installed in a spinning missile or thelike. It comprises a body member or stator 10 which is generallycylindrical in form, with an annular wall providing a cylindricalchamber in which a rotor 11 is mounted. The arrangement of this fuze issuch that when the rotor member is positioned counterclockwise relativeto the body member then the fuze is fully armed (FIG. 5 When the rotormember is positioned near its clockwise limit then the fuze is safe(FIG. 3). When the rotor is approximately at its clockwise limit thefuze becomes pre-arrned (FIG. 4).

Torque urging the rotor member toward its counterclockwise or firingposition is provided by an energy storage means in the form of a spiraltorsion spring 12, one end of which is fastened to the rotor and theother end of which is secured to the stator 10.

The parts now described function in static condition or in cooperationwith the centrifugal forces developed during the initial high rate ofspin of the missile and the later diminished spin, to restrain orcontrol the rotor in such a way that it is safed, pre-armed and armed,as desired.

A plurality of swingable weights or centrifugal forceresponsive elements13, 14 and 15 are pivotally mounted on the body member or stator 10 atpoints symmetrically disposed thereon and located degrees from eachother, with their pivots 16, 17 and 18 at the same radial distances withrespect to the central axis of the rotor and the housing or stator. Adetonator 19 is carried on the outer end of the weight 15 which ishereinafter variously referred to as the detonator-carrying weight orcarriage element. The other weights 13 and 14 are hereinafter referredto as safety weights or safety elements for reasons explained below. Thethree gross weights are identical in size, weight and configuration,this statement assuming that the weight of the stab-sensitive type ofdetonator 19 is effectively included in the figure for thedetonator-carrying weight.

The weights swing within two plane surfaces formed by a face plate 20 onone side and the rotor 11 on the other.

Disposed with its point projecting into a central aperture 21 in rotor11 is a firing pin 22 which is positioned by a spring plate 23. Thefiring pin is caged within a cover 24 which is preferably fitted intothe plate 20 in such a manner that the entire fuze assembly is ahermetically sealed unit.

Referring now briefly to FIGS. 3, 4 and 5, they illustrate the parts inthe safe, pre-arm and arm positions, respectively. In the safe positionthe swingable weights 13, 14 and 15 are symmetrically disposed withtheir outer or flee end displaced sufiiciently radially outwardly thatthe detonator 19 is out of line with the firing train (i.e. withaperture 21), in fact so substantially out of line that the detonatorcannot initiate an explosion even if accidentally considerablydisplaced. In this position, cam projections on the weights 13 and 14prevent the rotor from turning counterclockwise. In the safe position,the fuze is both statically and dynamically balanced, and is notsensitive to shocks or vibrations in the direction parallel to the axisof the housing, there being then no force tending to swing any of thethree weights. As to forces parallel to the rotor, any tendency of anyof the weights to rotate is resisted because they are all restrained bygrooves formed in the rotor, the result being that the rotor remainslocked.

More specifically, the rotor member is formed with locking grooves 25and 26, diagonally extending radially inwardly and clockwise. Theselocking grooves accept cam-like projections 27 and 28, formed on thesafety weights. In the safe position, safety weight projection 27 abutsagainst the inner end of locking groove 25 and safety weight projection23 abuts against the inner end of locking groove 26, whereby the rotor11 is restrained against counterclockwise movement. Additionally, therotor exerts tangential force which keep the weights 13 and 14 fromswinging outwardly.

Referring now to the detonator-carrying weight 15, it is formed with acam-like projection 29 that fits into an arcuate holding and positioninggroove 30 which is cut in the rotor 11. The holding and positioninggroove is formed clockwise. It extends radially inwardly with aclockwise lead. In the safe position the concave or left hand side ofthis groove (as viewed in FIG. 3) exerts a restraining force on theweight 15 and prevents it from swinging, so that all three of theweights are locked in place as against forces of the order encounteredduring the usual handling and storage and firing-preparation andinstallation of the fuze. That is to say, in the absence of centrifugalforces of sufiicient strength to swing all of the safety weightsoutwardly the fuze is safe (FIG. 3) and, for all practical purposes, thedetonator 19 cannot be aligned with the firing train.

Let us now consider the pre-armed condition illustrated in FIG. 4. Theaction of the centrifugal force imparted to the weights when the missilecarrying the fuze spins at a high rate during flight is such as toovercome the spring-urged restraint on the weights imposed by the rotor,whereby the free ends of the weights swing radially outwardly, turningthe rotor 11 slightly clockwise, freeing the projections 28 and 27 fromthe locking grooves 26 and 25, respectively. That is, the projections onthe safety weights are disengaged from the locking groove portions ofthe locking and positioning formations. Reiteratin-g, only undercentrifugal force attained when the fuze is rotating about its geometricaxis do the forces against the three weights cause them to rotate orswing about their respective axes or pivots and to swing outwardly. Eachcam-like projection then exerts a force against its respective camgroove, as the case may be, and when the three combined forces result ina torque greater than that of the spiral spring 12, the rotor turnsslightly clockwise. As the rotor begins this slight angulardisplacement, each of the weights swing further outwardly so that arapid transition is made from the safe to the prearmed positionillustrated in FIG. 4, at which the free ends of all three weights areat their maximum outward positions. Under this condition of operationthe detonator-carrying weight 15 functions as a holding weight and thearcuate groove 30 functions as a holding groove in that the left orconcave side (FIG. 4) of the groove 30 has exerted against it athrusting force by projection 29 on weight 15, which force preventsrotor 11 from turning counterclockwise. In other words, the projection29 exerts a clockwise force against the holding groove 30 to restrainthe rotor against counterclockwise displacement during the pre-armedphase of operation.

As the spin of the missile decreases, the spring-urged counterclockwiseand radially inward force exerted by the right or convex side of groove30 against cam projection 29 begins to prevail over the action of thecentrifugal force on weight 15 and weight 15 accordingly begins to swinginwardly. This is made possible by the fact that the locking grooves 25and 26 are fore-shortened and are formed in communication with arcuatepositioning grooves 32 and 33. These are formed in the rotor member withradially inward and clockwise leads in order to permit counterclockwiserotation of the rotor 11 (urged by the spring) to swing the lockingweights 13 and 14 inwardly (FIG. 5). The formations 25, 32 and 26, 33are therefore referred to as locking and positioning formations.

Stating the initiation of the arming phase in another way: As the spinof the missile diminishes, a threshold is reached at which therest-raining torque against the rotor 11 exerted by the tangentialcomponents of the detonator holding weight is less than the torque ofthe spring 12. At this time the rotor begins to move counterclockwise,rotating the ends of all the weights inwardly, the inward radial lead ofgroove 30 being substantially greater than that of grooves 32 and 33.The free end of the detonator carrying weight 15 is therefore swung muchfurther inwardly than the free ends of the other two weights in order toalign the detonator 19 with the firing train (FIG. 5). A significantaspect of the arming sequence i that, once the weights begin to rotateinwardly, the unbalance between centrifugal force and the constantspiral spring torque rapidly increases, thereby providing a rapidtransition from the re-ar-med to the fully armed position illustrated inFIG. 5.

Upon impact of the missile, the inertial firing pin 22 moves forwardagainst the restraint of spring plate 23 to penetrate detonator 19 andinitiate explosion.

While there has been shown what is at present considered to be thepreferred embodiment of this invention, it will be understood by thoseskilled in the art that various changes and modifications may be madetherein without departing from the proper scope of the invention asdefined in the claims.

For example, the missile here spins clockwise and, pin 22 pointingforwardly, the FIG. 1 embodiment spins counterclockwise. The FIG. 1embodiment also operates in a counterclockwise spinning missile.

Having fully disclosed our invention, we claim:

1. In a mechanical fuze the combination of a rotor having a plurality oflocking and positioning formations and a holding and positioningformation, energy storage means urging the rotor in one angulardirection;

a stator;

a plurality of swingable centrifugal-force responsive safety elementsmounted on the stator and formed to engage the locking portions of thelocking and posi= tioning formations on the rotor and to restrain therotor against angular motion in said direction until a threshold ofcentrifugal force is attained, a detonator, a swingablecentrifugal-force-responsive detonator-carriage element mounted on thestator and formed to engage the holding portion of the holding andpositioning formation to continue to hold the rotor against movement inthat direction even after said threshold is attained, the attainment ofsuch threshold swinging the safety elements sufficiently to disengagethem from the locking portions and to engage them with the positioningportions of the locking and positioning formations, whereupon thecarriage element continues to engage the holding portion of the holdingand positioning formation to hold the rotor until the centrifugal forcediminishes to such an extent as to permit the rotor to begin to turn insaid direction whereupon the safety elements and carriage element arepositioned radially inwardly by their respective positioning formationsto place the detonator in armed position.

2. In a mechanical fuze for a missile having a firing train, thecombination of a rotor having an axis in line with said firing train andalso having a plurality of locking and positioning formations and aholding and positioning formation, energy storage means urging the rotorin one angular direction, a stator in which the rotor is mounted, andmeans for controlling the rotor to place it in safe, pre-armed, andarmed positions, comprising:

a plurality of swingable safety weights mounted on the stator and formedto engage the locking and positioning formations on the rotor and tolock the rotor safe against angular motion in said direction;

being formed with a cam projection;

6 weights, the other weights being identified as safety weights; therotor member being formed with locking grooves diagonally extendingradially inwardly and clocka detonator; 5 wise, individual lockinggrooves being provided to another swingable detonator-carrying weightmounted accept the projections on the safety weights;

on the housing and formed to engage the holding an arcuate holding andpositioning groove, formed portion of the holding and positioningformation to clockwise in said rotor and extending inwardly withrestrain the rotor against angular motion in that dia radial andclockwise lead which accepts the projecrection, all of theaforementioned weights being lo- 10 tion on the detonator-carrymgweight, the locking cated symmetrically to maintain static and dynamicgrooves being so formed as to engage the pro ections balance, saidsafety weights beingresponsive to the on the safety weights to restrainthe rotor against centrifugal forces developed by sp n to be displacedcounterclockwise movement, whereby the rotor is sufficiently radiallyoutwardly to disengage the safety locked in a safe clockwise position inthe absence of weights from the locking portions of the locking andcentrifugal forces which swing the safety weights positioning formationsand to engage them with the outwardly, the-action of centrifugal forceimparted positioning polrtiltlms offtthe locllltingi anld positioningwltienb the missl lle cattrrying theh fuzef spins atha high ormations, at' e sa e y weig ts isp acing e rora e emg suc as 0 swing e sa ety weigts outtor sufliciently in the reverse angular direction to acwardly,whereby the projections on the safety weights complish such disenigagerent, wherguplintihthg rotor tfiisenglige fromt the loctlging1 groozes topre-armtlliltz assumes a pre-arme con i ion in w ic e e onauze, e pro ecion on e e ona or-carrymg weig tor-carrying weight restrains the rotorby engagecontinuing to be urged outwardly to exert a clockment with theholding portion of the holding and wise thrust against the holdingportion of the holdpositioning formation, diminution in said centrifugaling and positioning groove to restrain the rotor durforces due todirrlilinishing spinbreducingi the restiraint ing tllie pre-agmedpltilase ofh operation handhuntil tihe and permitting t e rotor to emove in sai anmissie spin iminis es, w ereupon t e t rust egulardirection, whereby the positioning portions of creases to permitcounterclockwise rotation of the the locking and positioning formationsswing the rotor in response to the spring, arcuate positioning safetyweights radially inward and the positioning grooves in communicationwith said locking grooves portion of the holding and positioningformation and formed in such rotor member with a radially inslwmgs thedetonaltlorifary ng :ve ght ll'lvlgald is, aflign glard andtclockwiseflllead E0; permithsaid rotaitlion lof t e detonator wit t ering rain, so t at t e uze e ro or 0 swing e sa e y weig ts inwar y, t eassumes an armed condition. positioning portion of the arcuate holdingand posi- 3. A mechanical fuze adapted to be installed in a tioninggroove simultaneously swinging the detonaspinning missile or the likecomprising: tor-carrying weight inwardly, that holding and posia bodymember; tioning groove having sufiicient length that as the a rotorwithin the body member constructed and ardetonatoracarrying weightswings inwardly the detranged to be positioned counterclockwise when theonator is aligned with an axially positioned firing fuze is armed; trainto arm the fuze. a torsion spring between the body member and the 40rotor for turning the rotor counterclockwise unless References Cited ythe Examiner the rotor is restrained; UNITED STATES PATENTS a pluralityof weights having leading ends and trailing ends and pivotally mountedon the body member at 3 1 et a1 1O2 '79 points symmetrically disposedthereon, each weight lane 1 102 79 BENJAMIN A. BORCHELT, PrimaryExaminer. G. H. GLANZMAN, Assistant Examiner.

adetonator carried on the outer end of one of said

1. IN A MECHANICAL FUZE THE COMBINATION OF A ROTOR HAVING A PLURALITY OFLOCKING AND POSITIONING FORMATIONS AND A HOLDING AND POSITIONINGFORMATION, ENERGY STORAGE MEANS URGING THE ROTOR IN ONE ANGULARDIRECTION; A STATOR; A PLURALITY OF SWINGABLE CENTRIFUGAL-FORCERESPONSIVE SAFETY ELEMENTS MOUNTED ON THE STATOR AND FORMED TO ENGAGETHE LOCKING PORTIONS OF THE LOCKING AND POSITIONING FORMATIONS ON THEROTOR AND TO RESTRAIN THE ROTOR AGAINST ANGULAR MOTION IN SAID DIRECTIONUNTIL A THRESHOLD OF CENTRIFUGAL FORCE IS ATTAINED, A DETONATOR, ASWINGABLE CENTRIFUGAL-FORCE-RESPONSIVE DETONATOR-CARRIAGE ELEMENTMOUNTED ON THE STATOR AND FORMED TO ENGAGE THE HOLDING PORTION OF THEHOLDING AND POSITIONING FORMATION TO CONTINUE TO HOLD THE